Method and device for determining magnetic losses for residual field weakening control

Abstract

The application provides a magnetic loss determination method and device applied to residual magnetic weakening control, and relates to the technical field of power transformers. The method comprises the following steps: obtaining a direct-current bias magnetic condition and magnetic loss data of electrical steel under a direct-current non-bias magnetic condition; estimating, through a preset elliptical static loss calculation model, an upper half branch bias magnetic static hysteresis loop enclosed area and a lower half branch bias magnetic static hysteresis loop enclosed area of the electrical steel under the direct-current bias magnetic condition, and adding the two areas to obtain a static hysteresis loss; calculating, according to the direct-current bias magnetic condition, an eddy current loss generated by the electrical steel under the direct-current bias magnetic condition; calculating, according to the direct-current bias magnetic condition and the magnetic loss data, an abnormal loss generated by the electrical steel under the direct-current bias magnetic condition; and superimposing the static hysteresis loss, the eddy current loss and the abnormal loss to obtain the magnetic loss of the electrical steel under the direct-current bias magnetic condition. The application can break the dependence on measured magnetic loss data under the bias magnetic condition, and reduce the magnetic loss calculation complexity under the direct-current bias magnetic condition.

Description

Technical Field

[0001] This invention relates to the field of power transformer technology, and in particular to a method and device for determining magnetic losses applied to residual magnetism weakening control. Background Technology

[0002] The core material of a power transformer is electrical steel. Electrical steel is a soft magnetic material. Due to the hysteresis characteristics of soft magnetic materials, residual magnetism remains within the electrical steel after the power transformer is shut down. This residual magnetism needs to be eliminated or weakened. The process of weakening residual magnetism is essentially the magnetization process of the soft magnetic material (i.e., electrical steel) under DC bias conditions. The nonlinear energy loss (i.e., magnetic loss) generated during the magnetization process under DC bias conditions is the key factor determining the demagnetization process and its effectiveness. Therefore, accurately simulating the magnetic loss of electrical steel under bias conditions is beneficial to improving the residual magnetism weakening effect of power transformers.

[0003] The calculation method for magnetic loss of electrical steel under DC bias conditions in related technologies relies on a large amount of measured magnetic loss data under bias conditions to build relevant models or simulate and calculate the corresponding parameters before a relatively accurate prediction can be achieved, resulting in high computational complexity. Summary of the Invention

[0004] This invention provides a method and apparatus for determining magnetic loss in remanence weakening control, thereby reducing the computational complexity of magnetic loss calculation under DC bias conditions by eliminating the reliance on measured magnetic loss data under bias conditions when calculating the magnetic loss of electrical steel.

[0005] In a first aspect, embodiments of the present invention provide a method for determining magnetic loss applied to remanence weakening control, comprising: Obtain magnetic loss data of electrical steel under DC bias conditions and DC unbiased conditions; Based on the DC bias conditions and the magnetic loss data, the area enclosed by the upper half of the bias static hysteresis loop and the area enclosed by the lower half of the bias static hysteresis loop of the electrical steel under the DC bias conditions are estimated using a preset elliptical static loss calculation model. The areas enclosed by the upper half of the bias static hysteresis loop and the lower half of the bias static hysteresis loop are then added together to obtain the static hysteresis loss of the electrical steel under the DC bias conditions. Based on the DC biasing condition, calculate the eddy current loss generated by the electrical steel under the DC biasing condition; Based on the DC bias conditions and the magnetic loss data, the abnormal loss coefficient of the electrical steel is calculated, and based on the abnormal loss coefficient, the abnormal loss generated by the electrical steel under the DC bias conditions is calculated. The static hysteresis loss, eddy current loss, and abnormal loss under the DC bias condition are superimposed to obtain the magnetic loss of the electrical steel under the DC bias condition.

[0006] In one possible implementation, estimating the area enclosed by the upper and lower halves of the static hysteresis loop of the electrical steel under the DC bias conditions, based on the DC bias conditions and the magnetic loss data, using a preset elliptic static loss calculation model, includes: Obtain the DC magnetization curve of the electrical steel material; Based on the DC bias conditions and the DC magnetization curve of the material, calculate the actual maximum magnetic flux density of the electrical steel under the DC bias conditions; Based on the magnetic loss data and the actual maximum magnetic flux density, estimate the static hysteresis loop coercivity of the electrical steel under the DC bias condition, the magnetization coefficient corresponding to the upper half bias static hysteresis loop, and the magnetization coefficient corresponding to the lower half bias static hysteresis loop. Based on the coercivity of the static hysteresis loop and the magnetization coefficient corresponding to the upper half of the biased static hysteresis loop, the area enclosed by the upper half of the biased static hysteresis loop of the electrical steel under the DC biased magnetic conditions is estimated using the elliptical static loss calculation model. Based on the coercivity of the static hysteresis loop and the magnetization coefficient corresponding to the lower half of the biased static hysteresis loop, the area enclosed by the lower half of the biased static hysteresis loop of the electrical steel under the DC biased magnetic conditions is estimated using the elliptical static loss calculation model.

[0007] In one possible implementation, estimating the static hysteresis loop coercivity of the electrical steel under the DC bias condition based on the magnetic loss data and the actual maximum magnetic flux density includes: Based on the magnetic loss data, determine the coercivity corresponding to the unbiased static hysteresis loop of the electrical steel when the magnetic flux density amplitude of the electrical steel is the actual maximum magnetic flux density. The coercivity corresponding to the unbiased static hysteresis loop of the electrical steel is determined as the coercivity of the static hysteresis loop generated by the electrical steel under the DC biased magnetic condition.

[0008] In one possible implementation, the magnetization coefficient corresponding to the upper half-branch biased static hysteresis loop is estimated based on the magnetic loss data and the actual maximum magnetic flux density, including: Based on the magnetic loss data, the magnetization coefficient corresponding to the unbiased static hysteresis loop of the electrical steel is determined when the magnetic flux density amplitude of the electrical steel is the actual maximum magnetic flux density, and the first magnetization coefficient is obtained. The first magnetization coefficient is determined to be the magnetization coefficient corresponding to the upper half-branch biased static hysteresis loop.

[0009] In one possible implementation, the magnetization coefficient corresponding to the lower half-branch biased static hysteresis loop is estimated based on the magnetic loss data and the actual maximum magnetic flux density, including: Based on the DC bias conditions, determine the DC magnetic flux density of the electrical steel under the DC bias conditions; Based on the magnetic loss data, the magnetization coefficient corresponding to the unbiased static hysteresis loop of the electrical steel is determined when the magnetic flux density amplitude of the electrical steel is a preset magnetic flux density, and the second magnetization coefficient is obtained. The second magnetization coefficient is determined to be the magnetization coefficient corresponding to the lower half-branch biased static hysteresis loop; Wherein, the preset magnetic flux density is twice the DC magnetic flux density, and the absolute value of the difference between the actual maximum magnetic flux density.

[0010] In one possible implementation, estimating the area enclosed by the upper half of the biased static hysteresis loop of the electrical steel under DC bias conditions using the elliptical static loss calculation model, based on the coercivity of the static hysteresis loop and the magnetization coefficient corresponding to the upper half of the biased static hysteresis loop, includes: Based on the DC bias conditions, determine the maximum AC magnetic flux density of the electrical steel under the DC bias conditions; Based on the coercivity of the static hysteresis loop and the maximum AC magnetic flux density, and in accordance with the elliptical curve establishment rules of the elliptical static loss calculation model, a semi-elliptical curve corresponding to the upper half biased static hysteresis loop is established, and the first elliptical area of ​​the semi-elliptical curve is calculated. Multiply the area of ​​the first ellipse by the magnetization coefficient corresponding to the upper half of the biased static hysteresis loop to obtain the area enclosed by the upper half of the biased static hysteresis loop.

[0011] In one possible implementation, estimating the area enclosed by the lower half of the biased static hysteresis loop of the electrical steel under DC bias conditions using the elliptical static loss calculation model, based on the coercivity of the static hysteresis loop and the magnetization coefficient corresponding to the lower half of the biased static hysteresis loop, includes: Based on the DC bias conditions, determine the maximum AC magnetic flux density of the electrical steel under the DC bias conditions; Based on the coercivity of the static hysteresis loop and the maximum AC magnetic flux density, and in accordance with the elliptical curve establishment rules of the elliptical static loss calculation model, a semi-elliptical curve corresponding to the lower half-branch biased static hysteresis loop is established, and the area of ​​the second ellipse of the semi-elliptical curve is calculated. Multiply the area of ​​the second ellipse by the magnetization coefficient corresponding to the lower half of the biased static hysteresis loop to obtain the area enclosed by the lower half of the biased static hysteresis loop.

[0012] In one possible implementation, calculating the eddy current loss generated by the electrical steel under the DC bias condition includes: Based on the DC bias conditions, determine the maximum AC magnetic flux density of the electrical steel under the DC bias conditions; according to Calculate the eddy current loss generated by the electrical steel under the DC bias magnetization condition; wherein, The eddy current loss generated by the electrical steel under the DC bias magnetization condition. The electrical conductivity of the electrical steel is given. d The thickness of the electrical steel is [missing information]. f The frequency of the DC bias condition is... The maximum alternating magnetic flux density is denoted as .

[0013] In one possible implementation, the step of calculating the abnormal loss coefficient of the electrical steel based on the DC bias condition and the magnetic loss data, and calculating the abnormal loss generated by the electrical steel under the DC bias condition based on the abnormal loss coefficient, includes: Based on the DC bias conditions, determine the maximum AC magnetic flux density and the actual maximum magnetic flux density of the electrical steel under the DC bias conditions; Based on the magnetic loss data, the abnormal loss coefficient corresponding to the actual maximum magnetic flux density and the abnormal loss coefficient corresponding to the maximum AC magnetic flux density are determined, and based on the abnormal loss coefficient corresponding to the actual maximum magnetic flux density and the abnormal loss coefficient corresponding to the maximum AC magnetic flux density, the abnormal loss coefficient of the electrical steel is determined. according to Calculate the abnormal losses generated by the electrical steel under the DC bias magnetic condition; wherein, This refers to the abnormal loss generated in the electrical steel under the DC bias magnetic condition. The abnormal loss coefficient is mentioned above; For the sign coefficient, ,when dB / dt When >0, When it is 1, dB / dt When <0, It is -1.

[0014] In a second aspect, embodiments of the present invention provide an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the method described in the first aspect or any possible implementation thereof.

[0015] The beneficial effects of the embodiments of the present invention compared with the prior art are as follows: This invention utilizes magnetic loss data of electrical steel under DC bias conditions and DC unbiased conditions to calculate the areas enclosed by the upper and lower half of the static hysteresis loop under DC bias conditions. This allows for the calculation of the static hysteresis loss of the electrical steel under DC bias conditions. Furthermore, the abnormal loss and eddy current loss under DC bias conditions can be calculated using the magnetic loss data under DC unbiased conditions. By superimposing the static hysteresis loss, eddy current loss, and abnormal loss under DC bias conditions, the magnetic loss of the electrical steel under DC bias conditions can be obtained. This invention directly calculates the magnetic loss under DC bias conditions using the magnetic loss data of electrical steel under DC unbiased conditions, eliminating the need to train relevant models or calculate relevant parameters based on measured magnetic loss data under DC bias conditions. This reduces reliance on measured magnetic loss data under DC bias conditions and simplifies computational complexity. Attached Figure Description

[0016] Figure 1 This is the implementation flow of the magnetic loss determination method for remanence weakening control provided in the embodiments of the present invention. Figure 1 ; Figures 2(a)-2(b) are schematic diagrams of the upper half-branch biased static hysteresis loop and the lower half-branch biased static hysteresis loop under biased magnetic conditions provided in the embodiments of the present invention. Figure 3 This is the second flowchart of the implementation of the magnetic loss determination method for remanence weakening control provided in this embodiment of the invention; Figures 4(a)-4(d) are schematic diagrams comparing the magnetization coefficients of the static hysteresis loop under biased and unbiased conditions provided in the embodiments of the present invention. Figure 5 This is a schematic diagram of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0017] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0018] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0019] The core material of a power transformer is electrical steel, a type of soft magnetic material. Due to the hysteresis characteristics of soft magnetic materials, electrical steel retains residual magnetism after shutdown or inspection. This residual magnetism can adversely affect the power transformer. For example, the presence of residual magnetism can cause deep saturation of the core during no-load switching, resulting in inrush currents that can reach 6 to 8 times the rated current, thereby damaging the mechanical structure of the equipment and threatening the safe operation of the system. Therefore, it is necessary to eliminate or weaken the residual magnetism within the power transformer. The resistor-inductor-capacitor (RLC) energy oscillation demagnetization method is an effective means of weakening residual magnetism. The residual magnetism weakening process is essentially a magnetization process of the soft magnetic material (i.e., electrical steel) under DC bias conditions. The nonlinear energy loss (i.e., magnetic loss) generated during magnetization is the key factor determining the demagnetization process and its effectiveness. Therefore, accurately calculating the magnetic loss of electrical steel under bias conditions is a prerequisite for optimizing the RLC energy oscillation demagnetization strategy and improving the demagnetization effect of the power transformer.

[0020] In related technologies, the calculation methods for magnetic losses of electrical steel under DC bias conditions can be divided into the following three types: (1) Loss lookup table method. The loss lookup table method requires a large amount of measured magnetic loss data under biased magnetic conditions to establish a mapping relationship and then look up the data in the table.

[0021] (2) Empirical formula method. The Steinmetz hysteresis loss formula is usually used for calculation, but this formula cannot directly consider the influence of DC bias. When analyzing the influence of bias on magnetic loss, the prediction accuracy is low. It is necessary to introduce an additional bias loss factor for correction. Moreover, this bias loss factor is mostly obtained by fitting magnetic loss data under bias conditions.

[0022] (3) Hybrid method based on hysteresis model and loss statistics theory. This method relies on the magnetic loss data under measured bias conditions to establish the corresponding model, and the calculation accuracy of the magnetic loss data also depends on the quantity and type of the magnetic loss data under measured DC bias conditions.

[0023] It is evident that most current methods for calculating magnetic loss under DC bias conditions rely on measured magnetic loss data of electrical steel under DC bias conditions. These methods require the use of a large amount of measured magnetic loss data under bias conditions to establish corresponding models or simulate relevant parameters, resulting in high computational complexity.

[0024] This application provides a method for determining magnetic loss in control of residual magnetism reduction. It can calculate and determine the magnetic loss generated by electrical steel under DC biased magnetism based on the magnetic loss data of electrical steel under DC unbiased magnetism. In this way, the magnetic loss of electrical steel under DC biased magnetism can be predicted more accurately using the unbiased magnetism loss data.

[0025] See Figure 1 The flowchart illustrating the implementation of the magnetic loss determination method for remanence weakening control provided by an embodiment of the present invention is described in detail below: Step 101: Obtain the magnetic loss data of the electrical steel under DC bias conditions and DC unbiased conditions.

[0026] Here, the DC bias condition can be parameters such as frequency. The magnetic loss data can be the static hysteresis loop of electrical steel under DC unbiased conditions.

[0027] Among them, the DC unbiased magnetic condition refers to the magnetization of electrical steel by using a DC unbiased magnetic field with a fixed direction, a variable magnetic field strength H, and no other bias magnetic field with a fixed direction (such as residual magnetism of electrical steel, external DC interference magnetic field, etc.).

[0028] The static hysteresis loop refers to the closed curve showing the change of magnetic flux density B of electrical steel with magnetic field strength H. In other words, this step obtains the static hysteresis loop of the electrical steel under DC unbiased magnetic conditions, showing the change of magnetic flux density B with magnetic field strength H. The static hysteresis loop can determine key magnetic characteristics of electrical steel such as remanence and coercivity, and is the core basis for evaluating its hysteresis loss and adapting it to equipment such as transformers.

[0029] Step 102: Based on the DC bias conditions and magnetic loss data, estimate the area enclosed by the upper and lower half of the static hysteresis loop of the electrical steel under DC bias conditions using a preset elliptical static loss calculation model. Then, add the areas enclosed by the upper and lower half of the static hysteresis loop to obtain the static hysteresis loss of the electrical steel under DC bias conditions.

[0030] In this embodiment, the static hysteresis loss can be calculated from the area of ​​the static hysteresis loop. The area of ​​the static hysteresis loop is essentially a direct quantitative representation of the static hysteresis loss generated by the hysteresis effect in one complete magnetization cycle of the electrical steel. That is, the static hysteresis loss can be obtained by calculating the area of ​​the static hysteresis loop.

[0031] The pre-defined elliptic static loss calculation model (also known as the elliptic loss model) is used to predict the static hysteresis loss of electrical steel under DC conditions. W hys Model: using static hysteresis loop coercivity H c-hys Magnetic flux density amplitude B max The area of ​​the elliptical hysteresis loop enclosed by the vertices is used to approximate the area of ​​the actual static hysteresis loop (the area of ​​the elliptical hysteresis loop is similar to the area of ​​the static hysteresis loop).

[0032] Referring to Figure 2, research revealed that for the static hysteresis loop of electrical steel under biased magnetization conditions, with B=0 as the dividing line, the static hysteresis loop under this biased magnetization condition can be divided into an upper biased static hysteresis loop (Figure 2(a)) and a lower biased static hysteresis loop (Figure 2(b)). Using the magnetic loss data under DC unbiased magnetization conditions, the areas of the upper and lower biased static hysteresis loops are calculated separately. Then, the sum of the areas of the upper and lower biased static hysteresis loops is calculated to obtain the area of ​​the static hysteresis loop under the entire biased magnetization condition, which is also the calculation of the static hysteresis loss under DC biased magnetization conditions.

[0033] Step 103: Calculate the eddy current loss generated by the electrical steel under DC bias conditions based on the DC bias conditions.

[0034] In this embodiment, the maximum AC magnetic flux density of the electrical steel under DC bias conditions can be determined based on the DC bias conditions. B ac-max ; to maximize AC magnetic flux density B ac-max Substituting the values ​​into the preset eddy current loss calculation formula, the eddy current loss generated by electrical steel under DC biased magnetization conditions is calculated.

[0035] The formulas for calculating eddy current loss include: ; in, This refers to the eddy current loss generated in electrical steel under DC bias conditions. The electrical conductivity of electrical steel, d For the thickness of electrical steel, f The frequency of the DC bias condition. This represents the maximum alternating magnetic flux density.

[0036] In this embodiment, for eddy current loss, when the magnetic flux density distribution inside the flexible magnetic tape in the time-varying electromagnetic field is relatively uniform, the eddy current loss is determined by the material conductivity and the rate of change of the average magnetic flux density. During the demagnetization process of the residual magnetism in the core of a large power transformer based on the RLC energy oscillation demagnetization method, its resonant frequency is generally below 50Hz. At this frequency, the magnetic flux density distribution inside the electrical steel strip is uniform, therefore the eddy current loss generated during the demagnetization process is relatively small. W eddy The classical eddy current loss prediction method can be used to solve the problem. That is, the above-mentioned preset eddy current loss prediction model can be used for calculation. It is not necessary to place the electrical steel under DC biased magnetic conditions and use relevant data for calculation. Instead, the frequency of the DC biased magnetic conditions on the electrical steel, the thickness of the electrical steel, and the conductivity can be used directly for calculation.

[0037] Step 104: Calculate the abnormal loss coefficient of electrical steel based on DC bias conditions and magnetic loss data, and calculate the abnormal loss generated by electrical steel under DC bias conditions based on the abnormal loss coefficient.

[0038] In this embodiment, abnormal losses can be calculated in the following way: Step 1041: Determine the maximum AC magnetic flux density of the electrical steel under DC bias conditions, based on the DC bias conditions. B ac-max and actual maximum magnetic flux density B actual-max .

[0039] Step 1042: Based on the magnetic loss data, determine the abnormal loss coefficient corresponding to the actual maximum magnetic flux density and the abnormal loss coefficient corresponding to the maximum AC magnetic flux density, and based on the abnormal loss coefficient corresponding to the actual maximum magnetic flux density and the abnormal loss coefficient corresponding to the maximum AC magnetic flux density, determine the abnormal loss coefficient of the electrical steel.

[0040] In this embodiment, the abnormal loss coefficient of electrical steel under DC unbiased magnetic conditions k a With magnetic flux density B max The static hysteresis loss of the material increases with the increase of the magnetic flux density, while under biased magnetization, the static hysteresis loss of the material is between the amplitude of the actual magnetic flux density under unbiased magnetization. B actual-max The corresponding static hysteresis loss and AC flux density amplitude B ac-max The corresponding static hysteresis losses. Considering that abnormal losses are determined by the static hysteresis losses generated by domain motion and the thermal effects of eddy currents, the presence of bias magnetism does not affect the eddy current losses of the material, but it will lead to an increase in the actual magnetic flux density, intensified domain rotation, and an increase in static hysteresis losses, thereby causing abnormal losses and the coefficient leading to abnormal losses. ka The increase, meaning the increment of abnormal loss under biased magnetization conditions, is only related to the increment of static hysteresis loss. Therefore, the abnormal loss coefficient under DC biased magnetization conditions... k a -d c It should also be within the range of the actual maximum magnetic flux density. B actual-max Corresponding abnormal loss coefficient k a -B actual-max With maximum alternating magnetic flux density B ac-max Corresponding abnormal loss coefficient k a -B ac-max Between. Therefore, the actual maximum magnetic flux density is determined respectively. B actual-max Corresponding abnormal loss coefficient k a - B actual-max and maximum alternating magnetic flux density B ac-max Corresponding abnormal loss system k a -B ac-max Then we can calculate. k a - B actual-max k a -B ac-max The average value is used as the abnormal loss coefficient under this DC bias condition. k a -d c .

[0041] Step 1043, regarding the calculation of abnormal losses, the relevant technology for solving abnormal losses of electrical steel. W exc The loss separation method is often used, as shown in the following formula: .

[0042] in, k a This is the abnormal loss coefficient. k a It is calculated by subtracting static hysteresis loss and eddy current loss from the measured magnetic loss.

[0043] Thisk a -d c Substituting this into the above as the abnormal loss coefficient, The formula yields the abnormal loss under DC unbiased magnetic conditions. ;in, This refers to the abnormal losses generated in electrical steel under DC bias conditions. This is the abnormal loss coefficient; For the sign coefficient, ,when dB / dt When >0, When it is 1, dB / dt When <0, It is -1.

[0044] Step 105: The static hysteresis loss, eddy current loss and abnormal loss under DC bias are superimposed to obtain the magnetic loss of electrical steel under DC bias.

[0045] This invention utilizes magnetic loss data of electrical steel under DC bias conditions and DC unbiased conditions to calculate the areas enclosed by the upper and lower half of the static hysteresis loop under DC bias conditions. This allows for the calculation of the static hysteresis loss of the electrical steel under DC bias conditions. Furthermore, the abnormal loss and eddy current loss under DC bias conditions can be calculated using the magnetic loss data under DC unbiased conditions. By superimposing the static hysteresis loss, eddy current loss, and abnormal loss under DC bias conditions, the magnetic loss of the electrical steel under DC bias conditions can be obtained. This invention directly calculates the magnetic loss under DC bias conditions using the magnetic loss data of electrical steel under DC unbiased conditions, eliminating the need to train relevant models or calculate relevant parameters based on measured magnetic loss data under DC bias conditions. This reduces reliance on measured magnetic loss data under DC bias conditions and simplifies computational complexity.

[0046] See Figure 3 As shown, in one possible implementation, step 102 may include: Step 1021: Obtain the DC magnetization curve of the electrical steel material.

[0047] Here, the DC magnetization curve of the material can specifically be the DC magnetization curve of electrical steel. B max -H b Curve. Among them, H b The value represents the DC bias magnetic field strength, indicating the intensity of the bias. B maxThis represents the maximum magnetic flux density that electrical steel can achieve after being superimposed with an additional magnetic field under the corresponding DC bias magnetic field strength.

[0048] Step 1022: Calculate the actual maximum magnetic flux density of electrical steel under DC bias conditions based on the DC bias conditions and the DC magnetization curve of the material.

[0049] From electrical steel B max -H b From the curve, the DC bias magnetic field strength corresponding to the DC bias condition can be determined. B max The determined B max This is the actual maximum magnetic flux density produced by the electrical steel under DC bias conditions. B actual-max .

[0050] Step 1023: Based on the magnetic loss data and the actual maximum magnetic flux density, estimate the coercivity of the static hysteresis loop of the electrical steel under DC bias conditions, the magnetization coefficient corresponding to the upper half of the biased static hysteresis loop, and the magnetization coefficient corresponding to the lower half of the biased static hysteresis loop.

[0051] (1) Calculation of coercivity of static hysteresis loop Based on theoretical analysis and experimental measurements, the coercivity of the bias magnetism on the static hysteresis loop was determined. H c-DC-hys The effects are as follows: When the maximum value of alternating magnetic flux density B ac-max When kept consistent, the coercivity of the static hysteresis loop of electrical steel under DC bias increases with increasing bias. At the actual maximum magnetic flux density... B actual-max When kept consistent, the maximum value of alternating magnetic flux density B ac-max The larger the DC magnetic field strength H dc The smaller. But regardless of alternating magnetic flux density B ac-max Regardless of the value, the static hysteresis loop of the left half of the electrical steel strictly follows the actual maximum magnetic flux density. B actual-max The left half of the corresponding static hysteresis loop is magnetized; while the right half of the static hysteresis loop will essentially return to the actual maximum magnetic flux density when the alternating magnetic flux density is 0. B actual-max The corresponding right half of the static hysteresis loop, and the magnetization process is completed along this right half. That is, regardless of the maximum value of the alternating magnetic flux density... Bac-max How large is it, when the actual maximum magnetic flux density is... B actual-max When the magnetic field is consistent, the coercivity of the static hysteresis loop under biased magnetic conditions is approximately equal to the actual maximum magnetic flux density under unbiased magnetic conditions. B actual-max The coercivity value of the corresponding static hysteresis loop.

[0052] Therefore, the calculation process for the coercivity of the static hysteresis loop generated by electrical steel under DC bias conditions can include: determining the coercivity corresponding to the unbiased static hysteresis loop of the electrical steel when the magnetic flux density amplitude of the electrical steel is the actual maximum magnetic flux density, based on magnetic loss data; and determining the coercivity corresponding to the unbiased static hysteresis loop of the electrical steel as the coercivity of the static hysteresis loop generated by the electrical steel under DC bias conditions. That is, determining the actual maximum magnetic flux density under DC unbiased conditions from the magnetic loss data. B actual-max The coercivity of the corresponding static hysteresis loop H c -B actual-max-hys This refers to the static hysteresis coercivity of the electrical steel under DC bias conditions. H c - DC-hys .

[0053] (2) Calculation of magnetization coefficient corresponding to the upper half of the biased static hysteresis loop In the elliptical static loss calculation model, the method of approximating the static hysteresis loop area with the elliptical area is problematic because as the magnetic flux density increases, the magnetic domain displacement gradually stops and the magnetic domains begin to rotate. The loss caused by the magnetic domain rotation is much higher than the loss caused by the magnetic domain displacement. As a result, the static hysteresis loss calculated by directly replacing the static hysteresis loop area with the elliptical area will be much lower than the actual static hysteresis loss.

[0054] Therefore, to address this issue, considering the influence of magnetization conditions on the static hysteresis loss of electrical steel, a magnetization coefficient is introduced. k Multiply the area of ​​the ellipse by the magnetization coefficient k The area of ​​the static hysteresis loop is then obtained. That is, k =Area of ​​static hysteresis loop / Area of ​​ellipse.

[0055] Figure 4(a) shows in B ac-max An example diagram of the upper half of the biased static hysteresis loop under a T = 1.4T condition, showing the magnetization coefficient corresponding to the upper half in this example. k 1 is 2.02. Figure 4(b) shows the magnetic flux density amplitude under unbiased conditions.B max =1.8T (that is, B max =B actual-max An example diagram of the static hysteresis loop, in which the magnetization coefficient of the unbiased static hysteresis loop is shown. k The value is 1.94. Combining Figures 4(a) and 4(b), it can be seen that the magnetization coefficient of the upper half of the static hysteresis loop under DC bias conditions... k 1. The actual magnetic flux density amplitude under DC unbiased magnetic conditions is the above-mentioned actual maximum magnetic flux density. B actual-max Magnetization coefficient of the static hysteresis loop at time k They are quite similar.

[0056] Therefore, the process of determining the magnetization coefficient corresponding to the upper half-branch biased static hysteresis loop includes: based on magnetic loss data, determining the magnetization coefficient corresponding to the unbiased static hysteresis loop of the electrical steel when the magnetic flux density amplitude of the electrical steel is the actual maximum magnetic flux density, thus obtaining the first magnetization coefficient; and determining the first magnetization coefficient as the magnetization coefficient corresponding to the upper half-branch biased static hysteresis loop. Specifically, from the magnetic loss data under DC unbiased conditions, the actual maximum magnetic flux density under unbiased conditions can be obtained using linear interpolation. B actual-max The corresponding magnetization coefficient k That is, the first magnetization coefficient, which is the magnetization coefficient corresponding to the upper half of the biased static hysteresis loop. k 1.

[0057] (3) Calculation of magnetization coefficient corresponding to the lower half of the biased static hysteresis loop Figure 4(c) shows the biased magnetization condition ( B ac =1.4T, H dc An example diagram of the lower half of the biased static hysteresis loop (20 A / m), in which the magnetization coefficient of the lower half of the biased static hysteresis loop is shown. k 2 is 1.05. Figure 4(d) shows the magnetic flux density amplitude under unbiased conditions. B max =1.0T (that is, B max = An example diagram of the static hysteresis loop, showing the magnetization coefficient of the unbiased static hysteresis loop in this example. k The value is 1.11. Combining Figures 4(c) and 4(d), it can be seen that the magnetization coefficient of the lower half of the static hysteresis loop under DC bias conditions is...k 2 is approximately equal to the actual magnetic flux density amplitude under DC unbiased magnetic conditions. Magnetization coefficient of the static hysteresis loop at time k .in, denoted as DC magnetic flux density under DC bias conditions.

[0058] Therefore, the calculation process for the magnetization coefficient corresponding to the lower half-branch biased static hysteresis loop can include: Determine the DC magnetic flux density of electrical steel under DC bias conditions. Based on the magnetic loss data, the magnetization coefficient corresponding to the unbiased static hysteresis loop of the electrical steel is determined when the magnetic flux density amplitude of the electrical steel is the preset magnetic flux density, thus obtaining the second magnetization coefficient. This second magnetization coefficient is then defined as the magnetization coefficient corresponding to the lower half-branch biased static hysteresis loop. k 2. Wherein, the absolute value of the difference between the preset magnetic flux density (twice the DC magnetic flux density) and the actual maximum magnetic flux density, i.e. .

[0059] Step 1024: Based on the coercivity of the static hysteresis loop and the magnetization coefficient corresponding to the upper half of the biased static hysteresis loop, estimate the area enclosed by the upper half of the biased static hysteresis loop of the electrical steel under DC biased conditions using the elliptical static loss calculation model.

[0060] The area enclosed by the upper biased static hysteresis loop can be calculated by multiplying the area of ​​the semi-ellipse corresponding to the upper biased static hysteresis loop by the magnetization coefficient corresponding to the upper biased static hysteresis loop. k 1. Calculated and obtained.

[0061] In some embodiments, the area enclosed by the upper bias static hysteresis loop is calculated based on the estimated coercivity of the static hysteresis loop, the magnetization coefficient corresponding to the upper bias static hysteresis loop, and a preset elliptical static loss calculation model. Specifically, this may include: Based on the DC bias condition, determine the maximum AC magnetic flux density present in the electrical steel (i.e., the maximum value of the AC magnetic flux density mentioned above). B ac-max Based on the above-determined static hysteresis loop coercivity... H c-DC-hys (Equal to the actual maximum magnetic flux density under unbiased magnetic conditions) B actual-max Corresponding static hysteresis loop coercivity H c -B actual-max-hys and maximum alternating magnetic flux density B ac-maxFollowing the preset elliptic curve establishment rules, a semi-elliptic curve corresponding to the upper half of the biased static hysteresis loop is established. The preset elliptic curve establishment rules include: setting the coercivity of the static hysteresis loop... H c-hys As the minor axis of the semi-elliptic curve, the maximum AC magnetic flux density B ac-max As the semi-major axis of the semi-elliptic curve, establish the semi-elliptic curve corresponding to the upper biased static hysteresis loop. Then calculate the elliptical area of ​​this semi-elliptic curve, and multiply it by the magnetization coefficient corresponding to the upper biased static hysteresis loop to obtain the area enclosed by the upper biased static hysteresis loop.

[0062] The magnetization coefficient corresponding to the upper biased static hysteresis loop is the proportionality coefficient between the area of ​​the ellipse of the semi-elliptic curve and the area enclosed by the upper biased static hysteresis loop. Specifically, as shown in Figure 2(a), the area enclosed by the upper biased static hysteresis loop is the area enclosed by the solid line and the horizontal axis in Figure 2(a), and the semi-ellipse is the curve formed by the dashed line in Figure 2(a). The area of ​​the semi-ellipse is the area enclosed by the dashed line and the horizontal axis in the figure. The area enclosed by the upper biased static hysteresis loop is: .

[0063] Step 1025: Based on the coercivity of the static hysteresis loop and the magnetization coefficient corresponding to the lower half of the biased static hysteresis loop, estimate the area enclosed by the lower half of the biased static hysteresis loop of the electrical steel under DC biased conditions using the elliptical static loss calculation model.

[0064] Specifically, as shown in Figure 2(b), the solid line in Figure 2(b) represents the lower half of the biased static hysteresis loop. The area of ​​this lower half of the biased static hysteresis loop is the area of ​​the ellipse (dashed line) in Figure 2(b) multiplied by the magnetization coefficient corresponding to the lower half of the biased static hysteresis loop. k 2. The semi-elliptic curve in Figure 2(b) is: [The text abruptly ends here, likely due to an incomplete sentence or missing information.] H c-DC-hys (Actual maximum magnetic flux density under unbiased magnetic conditions) B actual-ma x Corresponding coercivity H c -B actual-max-hys Using the minor axis of the semi-elliptic curve, the maximum AC magnetic flux density mentioned above is... B ac-max The semi-elliptic curve corresponding to the lower half of the biased static hysteresis loop is established as the semi-major axis of the semi-elliptic curve. The area enclosed by this lower half of the biased static hysteresis loop is... The actual maximum magnetic flux density under unbiased magnetic conditions B actual-max The corresponding static hysteresis loop coercivity, k 2 represents the magnetization coefficient corresponding to the lower half of the biased static hysteresis loop.

[0065] Step 1026: Add the area enclosed by the upper half of the biased static hysteresis loop and the area enclosed by the lower half of the biased static hysteresis loop to obtain the static hysteresis loss of the electrical steel under DC bias conditions.

[0066] In other words, the formula for calculating the static hysteresis loss of electrical steel under DC bias conditions includes: .in, This refers to the static hysteresis loss of electrical steel under DC bias conditions. The area enclosed by the upper half of the biased static hysteresis loop; It represents the area enclosed by the lower half of the biased static hysteresis loop.

[0067] This embodiment introduces a magnetization coefficient and divides the static hysteresis loop into upper and lower halves of a biased static hysteresis loop. The magnetization coefficients corresponding to the two halves are estimated separately. These magnetization coefficients are then used to correct the elliptical areas corresponding to the upper and lower halves of the biased static hysteresis loop. The corrected elliptical areas are then used to replace the area of ​​the static hysteresis loop to calculate the static hysteresis loss. This method, compared to directly using the elliptical area as the static hysteresis loop area to calculate the static hysteresis loss, improves the accuracy of static hysteresis loss calculation under DC bias conditions.

[0068] Based on the above, in one embodiment, the overall formula for the magnetic loss determination method applied to remanence weakening control is as follows: .

[0069] The above design achieves the following technical effects: (1) The static hysteresis loss, eddy current loss, abnormal loss and total magnetic loss of electrical steel under DC biased conditions can be predicted relatively accurately by using the magnetic loss data under unbiased conditions. The magnetic loss of electrical steel under DC biased conditions can be obtained without obtaining the measured magnetic loss data under biased conditions. This simplifies the steps of training relevant models or calculating relevant parameters based on a large amount of measured magnetic loss data under biased conditions and reduces the computational complexity.

[0070] (2) In this embodiment, in order to address the problem that directly using the ellipse area to replace the hysteresis loop area to calculate static hysteresis loss in the preset elliptical static loss calculation model would result in errors leading to low accuracy of static hysteresis loss calculation, a magnetization coefficient is introduced to correct the ellipse area and then use it as the hysteresis loop area to calculate static hysteresis loss, thereby improving the accuracy of static hysteresis loss calculation.

[0071] (3) In this embodiment, considering that the static hysteresis loss under biased magnetic conditions is caused by the additional loss generated by the increase of actual magnetic flux density, the coercivity of the static hysteresis loop under biased magnetic conditions is calculated based on the amplitude of the actual magnetic flux density under biased magnetic conditions (i.e., the actual maximum magnetic flux density) and the coercivity of the static hysteresis loop corresponding to the actual maximum magnetic flux density under DC unbiased magnetic conditions, so as to improve the calculation accuracy of static hysteresis loss.

[0072] (4) In this embodiment, the influence of bias magnetism on the magnetization process of electrical steel is fully considered, and the magnetic loss (static hysteresis loss, eddy current loss and abnormal loss) under bias magnetism is calculated based on the magnetic loss data of electrical steel under non-bias magnetism conditions. It can also provide theoretical support for optimizing the RLC energy oscillation demagnetization strategy.

[0073] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0074] Figure 5 This is a schematic diagram of an electronic device provided in an embodiment of the present invention. For example... Figure 5 As shown, the electronic device 5 of this embodiment includes a processor 50 and a memory 51. The memory 51 stores a computer program 52. When the processor 50 executes the computer program 52, it implements the steps in the various method embodiments described above.

[0075] For example, computer program 52 may be divided into one or more modules / units, which are stored in memory 51 and executed by processor 50 to complete the present invention. The one or more modules / units may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of computer program 52 in electronic device 5.

[0076] Electronic device 5 may include, but is not limited to, processor 50 and memory 51. Those skilled in the art will understand that... Figure 5This is merely an example of electronic device 5 and does not constitute a limitation on electronic device 5. It may include more or fewer components than shown, or combine certain components, or different components. For example, electronic device 5 may also include input / output devices, network access devices, buses, etc.

[0077] The processor 50 can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or any conventional processor.

[0078] The memory 51 can be an internal storage unit of the electronic device 5, such as a hard disk or RAM. The memory 51 can also be an external storage device of the electronic device 5, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card. Furthermore, the memory 51 can include both internal and external storage units of the electronic device 5. The memory 51 is used to store the computer program 52 and other programs and data required by the electronic device 5. The memory 51 can also be used to temporarily store data that has been output or will be output.

[0079] For the sake of simplicity and clarity, only the above-described functional modules / units are used as examples. In practical applications, the functions described above can be assigned to different functional modules / units as needed. These modules / units can be implemented in hardware, software, or a combination of both.

[0080] This invention also provides a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, it implements the methods described in the above-described method embodiments.

[0081] This invention also provides a computer program product, including a computer program. When the computer program is executed by a processor, it implements the methods described in the above-described method embodiments.

[0082] Computer programs include computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. Computer-readable media can include: any entity or device capable of carrying computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc.

[0083] In the above embodiments, the descriptions of each embodiment have their own emphasis. Parts not detailed or described in a particular embodiment can be referred to in the relevant descriptions of other embodiments. Unless otherwise specified or in conflict with logic, the terminology and / or descriptions between different embodiments are consistent and can be referenced interchangeably. Technical features in different embodiments can be combined to form new embodiments based on their inherent logical relationships.

[0084] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A method for determining magnetic loss applied to remanence weakening control, characterized in that, include: Obtain magnetic loss data of electrical steel under DC bias conditions and DC unbiased conditions; Based on the DC bias conditions and the magnetic loss data, the area enclosed by the upper half of the bias static hysteresis loop and the area enclosed by the lower half of the bias static hysteresis loop of the electrical steel under the DC bias conditions are estimated using a preset elliptical static loss calculation model. The areas enclosed by the upper half of the bias static hysteresis loop and the lower half of the bias static hysteresis loop are then added together to obtain the static hysteresis loss of the electrical steel under the DC bias conditions. Based on the DC biasing condition, calculate the eddy current loss generated by the electrical steel under the DC biasing condition; Based on the DC bias conditions and the magnetic loss data, the abnormal loss coefficient of the electrical steel is calculated, and based on the abnormal loss coefficient, the abnormal loss generated by the electrical steel under the DC bias conditions is calculated. The static hysteresis loss, eddy current loss, and abnormal loss under the DC bias condition are superimposed to obtain the magnetic loss of the electrical steel under the DC bias condition. The step of estimating the area enclosed by the upper and lower halves of the static hysteresis loop of the electrical steel under the DC bias conditions, based on the DC bias conditions and the magnetic loss data, using a preset elliptical static loss calculation model, includes: Obtain the DC magnetization curve of the electrical steel material; Based on the DC bias conditions and the DC magnetization curve of the material, calculate the actual maximum magnetic flux density of the electrical steel under the DC bias conditions; Based on the magnetic loss data and the actual maximum magnetic flux density, estimate the static hysteresis loop coercivity of the electrical steel under the DC bias condition, the magnetization coefficient corresponding to the upper half bias static hysteresis loop, and the magnetization coefficient corresponding to the lower half bias static hysteresis loop. Based on the coercivity of the static hysteresis loop and the magnetization coefficient corresponding to the upper half of the biased static hysteresis loop, the area enclosed by the upper half of the biased static hysteresis loop of the electrical steel under the DC biased magnetic conditions is estimated using the elliptical static loss calculation model. Based on the coercivity of the static hysteresis loop and the magnetization coefficient corresponding to the lower half of the biased static hysteresis loop, the area enclosed by the lower half of the biased static hysteresis loop of the electrical steel under the DC biased magnetic conditions is estimated using the elliptical static loss calculation model.

2. The method for determining magnetic loss applied to remanence weakening control according to claim 1, characterized in that, Based on the magnetic loss data and the actual maximum magnetic flux density, estimate the static hysteresis coercivity of the electrical steel under the DC bias condition, including: Based on the magnetic loss data, determine the coercivity corresponding to the unbiased static hysteresis loop of the electrical steel when the magnetic flux density amplitude of the electrical steel is the actual maximum magnetic flux density. The coercivity corresponding to the unbiased static hysteresis loop of the electrical steel is determined as the coercivity of the static hysteresis loop generated by the electrical steel under the DC biased magnetic condition.

3. The method for determining magnetic loss applied to remanence weakening control according to claim 1, characterized in that, Based on the magnetic loss data and the actual maximum magnetic flux density, estimate the magnetization coefficient corresponding to the upper half-branch biased static hysteresis loop, including: Based on the magnetic loss data, the magnetization coefficient corresponding to the unbiased static hysteresis loop of the electrical steel is determined when the magnetic flux density amplitude of the electrical steel is the actual maximum magnetic flux density, and the first magnetization coefficient is obtained. The first magnetization coefficient is determined to be the magnetization coefficient corresponding to the upper half-branch biased static hysteresis loop.

4. The method for determining magnetic loss applied to remanence weakening control according to claim 1, characterized in that, Based on the magnetic loss data and the actual maximum magnetic flux density, estimate the magnetization coefficient corresponding to the lower half-branch bias static hysteresis loop, including: Based on the DC bias conditions, determine the DC magnetic flux density of the electrical steel under the DC bias conditions; Based on the magnetic loss data, the magnetization coefficient corresponding to the unbiased static hysteresis loop of the electrical steel is determined when the magnetic flux density amplitude of the electrical steel is a preset magnetic flux density, and the second magnetization coefficient is obtained. The second magnetization coefficient is determined to be the magnetization coefficient corresponding to the lower half-branch biased static hysteresis loop; Wherein, the preset magnetic flux density is twice the DC magnetic flux density, and the absolute value of the difference between the actual maximum magnetic flux density.

5. The method for determining magnetic loss applied to remanence weakening control according to claim 1, characterized in that, The step of estimating the area enclosed by the upper half of the biased static hysteresis loop of the electrical steel under DC bias conditions, based on the coercivity of the static hysteresis loop and the magnetization coefficient corresponding to the upper half of the biased static hysteresis loop, using the elliptical static loss calculation model, includes: Based on the DC bias conditions, determine the maximum AC magnetic flux density of the electrical steel under the DC bias conditions; Based on the coercivity of the static hysteresis loop and the maximum AC magnetic flux density, and in accordance with the elliptical curve establishment rules of the elliptical static loss calculation model, a semi-elliptical curve corresponding to the upper half biased static hysteresis loop is established, and the first elliptical area of ​​the semi-elliptical curve is calculated. Multiply the area of ​​the first ellipse by the magnetization coefficient corresponding to the upper half of the biased static hysteresis loop to obtain the area enclosed by the upper half of the biased static hysteresis loop.

6. The method for determining magnetic loss applied to remanence weakening control according to claim 1, characterized in that, The step of estimating the area enclosed by the lower half of the static hysteresis loop of the electrical steel under DC bias conditions using the elliptical static loss calculation model, based on the coercivity of the static hysteresis loop and the magnetization coefficient corresponding to the lower half of the biased static hysteresis loop, includes: Based on the DC bias conditions, determine the maximum AC magnetic flux density of the electrical steel under the DC bias conditions; Based on the coercivity of the static hysteresis loop and the maximum AC magnetic flux density, and in accordance with the elliptical curve establishment rules of the elliptical static loss calculation model, a semi-elliptical curve corresponding to the lower half-branch biased static hysteresis loop is established, and the area of ​​the second ellipse of the semi-elliptical curve is calculated. Multiply the area of ​​the second ellipse by the magnetization coefficient corresponding to the lower half of the biased static hysteresis loop to obtain the area enclosed by the lower half of the biased static hysteresis loop.

7. The method for determining magnetic loss applied to remanence weakening control according to any one of claims 1 to 6, characterized in that, The step of calculating the eddy current loss generated by the electrical steel under the DC bias condition includes: Based on the DC bias conditions, determine the maximum AC magnetic flux density of the electrical steel under the DC bias conditions; according to Calculate the eddy current loss generated by the electrical steel under the DC bias magnetization condition; wherein, The eddy current loss generated by the electrical steel under the DC bias magnetization condition. The electrical conductivity of the electrical steel is given. d The thickness of the electrical steel is [missing information]. f The frequency of the DC bias condition is... The maximum alternating magnetic flux density is denoted as .

8. The method for determining magnetic loss applied to remanence weakening control according to any one of claims 1 to 6, characterized in that, The step of calculating the abnormal loss coefficient of the electrical steel based on the DC bias condition and the magnetic loss data, and calculating the abnormal loss generated by the electrical steel under the DC bias condition based on the abnormal loss coefficient, includes: Based on the DC bias conditions, determine the maximum AC magnetic flux density and the actual maximum magnetic flux density of the electrical steel under the DC bias conditions; Based on the magnetic loss data, the abnormal loss coefficient corresponding to the actual maximum magnetic flux density and the abnormal loss coefficient corresponding to the maximum AC magnetic flux density are determined, and based on the abnormal loss coefficient corresponding to the actual maximum magnetic flux density and the abnormal loss coefficient corresponding to the maximum AC magnetic flux density, the abnormal loss coefficient of the electrical steel is determined. according to Calculate the abnormal losses generated by the electrical steel under the DC bias magnetic condition; wherein, This refers to the abnormal loss generated in the electrical steel under the DC bias magnetic condition. The abnormal loss coefficient is mentioned above; For the sign coefficient, ,when dB / dt When >0, When it is 1, dB / dt When <0, It is -1.

9. An electronic device, characterized in that, It includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement the method as described in any one of claims 1 to 8.

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